package com.sibu.yx.promotion.persistence.util;

import java.security.AlgorithmParameters;
import java.security.InvalidAlgorithmParameterException;
import java.security.Key;
import java.security.NoSuchProviderException;
import java.security.Security;
import java.util.Arrays;

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

import org.bouncycastle.jce.provider.BouncyCastleProvider;

import lombok.extern.slf4j.Slf4j;

@Slf4j
public class AESUtil {
	
	public static final AESUtil instance = new AESUtil();

    public static boolean initialized = false;

    /**
     * AES解密
     * @param content 密文
     * @return
     * @throws InvalidAlgorithmParameterException
     * @throws NoSuchProviderException
     */
    public byte[] decrypt(byte[] content, byte[] keyByte, byte[] ivByte) throws Exception {

        int base = 16;
        if (ivByte.length % base != 0) {
            int groups = ivByte.length / base + (ivByte.length % base != 0 ? 1 : 0);
            byte[] temp = new byte[groups * base];
            Arrays.fill(temp, (byte) 0);
            System.arraycopy(ivByte, 0, temp, 0, ivByte.length);
            ivByte = temp;
        }

        initialize();
        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding");
        Key sKeySpec = new SecretKeySpec(keyByte, "AES");

        cipher.init(Cipher.DECRYPT_MODE, sKeySpec, generateIV(ivByte));// 初始化
        byte[] result = cipher.doFinal(content);
        return result;
    }

    public static void initialize(){
        if (initialized) return;
        Security.addProvider(new BouncyCastleProvider());
        initialized = true;
    }

    //生成iv
    public static AlgorithmParameters generateIV(byte[] iv) throws Exception{
        AlgorithmParameters params = AlgorithmParameters.getInstance("AES");
        params.init(new IvParameterSpec(iv));
        return params;
    }

}
